Simultaneous Perturbation Stochastic Approximation Algorithm Combined with Neural Network and Fuzzy Simulation

In order to solve three kinds of fuzzy programming models, i.e. fuzzy expected value model, fuzzy chance-constrained programming model, and fuzzy dependent-chance pro-gramming model, a simultaneous perturbation stochastic approximation algorithm is proposed by integrating neural network with fuzzy simulation. At first, fuzzy simulation is used to generate a set of input-output data. Then a neural network is trained according to the set. Finally, the trained neural network is embedded in simultaneous perturbation stochastic approximation algorithm. Simultaneous perturbation stochastic approximation algorithm is used to search the optimal solution. Two numerical examples are presented to illustrate the effectiveness of the proposed algorithm.

Research on simultaneous localization and mapping for AUV by an improved method:Variance reduction FastSLAM with simulated annealing

At present,simultaneous localization and mapping(SLAM) for an autonomous underwater vehicle(AUV)is a research hotspot.Aiming at the problem of non-linear model and non-Gaussian noise in AUV motion,an improved method of variance reduction fast simultaneous localization and mapping(FastSLAM) with simulated annealing is proposed to solve the problems of particle degradation,particle depletion and particle loss in traditional FastSLAM,which lead to the reduction of AUV location estimation accuracy.The adaptive exponential fading factor is generated by the anneal function of simulated annealing algorithm to improve the effective particle number and replace resampling.By increasing the weight of small particles and decreasing the weight of large particles,the variance of particle weight can be reduced,the number of effective particles can be increased,and the accuracy of AUV location and feature location estimation can be improved to some extent by retaining more information carried by particles.The experimental results based on trial data show that the proposed simulated annealing variance reduction FastSLAM method avoids particle degradation,maintains the diversity of particles,weakened the degeneracy and improves the accuracy and stability of AUV navigation and localization system.

Simultaneous upscaling of two properties of reservoirs in one dimension using adaptive bandwidth in kernel function method

Upscaling of primary geological models with huge cells, especially in porous media, is the first step in fluid flow simulation. Numerical methods are often used to solve the models. The upscaling method must preserve the important properties of the spatial distribution of the reservoir properties. An grid upscaling method based on adaptive bandwidth in kernel function is proposed according to the spatial distribution of property. This type of upscaling reduces the number of cells, while preserves the main heterogeneity features of the original fine model. The key point of the paper is upscaling two reservoir properties simultaneously. For each reservoir feature, the amount of bandwidth or optimal threshold is calculated and the results of the upscaling are obtained. Then two approaches are used to upscaling two properties simultaneously based on maximum bandwidth and minimum bandwidth. In fact, we now have a finalized upscaled model for both reservoir properties for each approach in which not only the number of their cells, but also the locations of the cells are equal. The upscaling error of the minimum bandwidth approach is less than that of the maximum bandwidth approach.

Numerical simulation of flow interference between four cylinders in in-line square arrangement

In the present paper,two-and three-dimensional numerical simulations of the flow interference between four cylinders in an in-line square arrangement at Re = 200 are performed.Assisted with the two-dimensional(2-D) numerical simulation,the mean and fluctuating forces,Strouhal number(St) and vortex shedding pattern in the wake for each cylinder were analyzed with the spacing ratio(L /D) ranging from 1.5 to 6.0.It was found that,four different vortex modes(viz.,flip-flopping,shielding anti-phase-synchronized,in-phasesynchronized and anti-phase-synchronized) gradually appear with the increase of the L/D ratio.The average drag coefficient of the upstream cylinders is larger than that of the downstream cylinders,while the downstream cylinders usually undergo serious fluctuating forces.When the L/D ratio ranges from 3.0 to 4.0,the dominant frequency of the drag coefficient is equal to the value of St of upstream cylinders.This indicates that a simultaneous resonance in the in-flow and cross-flow directions may occur for some single structures of a multi-body oscillating system.For the 3-D numerical simulation,the L/D and aspect ratios are kept constant as 5.0 and 10,respectively.It was found that some vortices are formed in the wake of the upstream cylinders.Besides,with the same spacing ratio,the calculated drag coefficient and lift coefficient fluctuation are slightly larger than the 2-D results,but with a phase difference.

高真空激光等离子体的同步移相干涉诊断及仿真

为了解决在高真空环境下,等离子体膨胀迅速、外围羽流引起的条纹偏移小、单幅干涉条纹图难以检出的问题,采用同步移相干涉测试技术得到了1.333×10-4 Pa和1.333×10-3 Pa真空度下激光诱导铝等离子体电子密度分布;同时采用2维轴对称流体动力学模型,对高真空环境下激光诱导等离子体的膨胀过程进行了数值仿真,得到了电子密度的2维分布,并分析了数值仿真结果存在偏差的原因及改进方法。结果表明,等离子体的中心电子密度在50 ns时下降至1.4×1020 cm-3;数值仿真结果与实验结果吻合较好,验证了模型的正确性。该研究为高真空下激光等离子体的研究提供了一定的参考。

基于电磁计算的同时极化雷达成像仿真

雷达信号的电磁(EM)仿真对新体制雷达技术的研究具有重要价值。文中针对新体制同时极化雷达(SPR)回波信号开展EM仿真,提出了快速仿真方法,并在此基础上进行了高分辨雷达成像。首先,利用FEKO构建了雷达目标在4π空间里所有入射角度下的宽带全极化EM散射数据库;接着,在推导SPR目标回波信号模型的基础上,基于优化最小化方法以最小化互补积分旁瓣电平为准则设计了H、V发射通道的正交互补序列波形。最后,根据实际雷达对目标的视角和频率范围以调用数据库的方式“装配”得到相应的雷达回波信号。为了进一步验证所提方法,该文以F22模型为例开展了SPR成像仿真实验,并通过Pauli分解分析了幅相误差对目标极化散射特性测量的影响。

基于MATLAB/Simulink的单缸发动机动态仿真

以MATLAB的动态仿真工具箱Simulink为平台,应用联立约束法建立了单缸发动机曲柄连杆机构动态分析的仿真模型,并根据闭环矢量方程将相容性检验模块嵌入了仿真模型,代入S195柴油机的各项参数后执行仿真,结果表明该仿真方法能方便、准确地得到机构的运动、动力数据,能为机构的选型、优化设计提供参考依据。

邻近煤层同采巷道布置及安全错距优化研究

针对苏村煤矿6煤、10煤分层同采错距不合理,上下两工作面开采受动压的相互影响,造成工作面冒顶、片帮、支架折损等问题,通过采用理论分析、数值模拟以及工程应用相结合的方法对邻近煤层同采工作面巷道布设位置及错距进行了优化研究。研究结果表明:考虑不同开采方式下10煤层巷道围岩应力变化特征,确定上下煤层巷道采用对齐式布置;考虑下煤层开采时覆岩移动,下煤层区段煤柱应大于16.7 m;上下煤层同采时工作面合理错距在45 m左右。研究结果应用工程实践表明,同采期间工作面支架受力平稳,实现了邻近煤层安全高效同采,对类似条件下的煤层群开采具有重要的指导意义。

Simultaneous approach for simulation of a high-temperature gas-cooled reactor

The simulation of a high-temperature gas-cooled reactor pebble-bed module(HTR-PM) plant is discussed.This lumped parameter model has the form of a set differential algebraic equations(DAEs) that include stiff equations to model point neutron kinetics.The nested approach is the most common method to solve DAE,but this approach is very expensive and time-consuming due to inner iterations.This paper deals with an alternative approach in which a simultaneous solution method is used.The DAEs are discretized over a time horizon using collocation on finite elements,and Radau collocation points are applied.The resulting nonlinear algebraic equations can be solved by existing solvers.The discrete algorithm is discussed in detail;both accuracy and stability issues are considered.Finally,the simulation results are presented to validate the efficiency and accuracy of the simultaneous approach that takes much less time than the nested one.

The Improved Simulated Annealing Algorithm and Application in the Surface Wave Dispersion Inversion

The velocity distribution of layers from surface wave dispersion curve is a severely nonlinear program. Base on the Metropolis rule,we improved the simulated annealing algorithm to simultaneously inverse the velocities and thicknesses using the dispersion data and identified the Moho and the bottom of lithosphere. The application to the numerical examples with 5% noise shows the velocity RMS is 1. 56% between the non-linear results and the original models when the condition of selecting method for temperature parameters and initial temperature are satisfied. Using the pure dispersions of Rayleigh wave,the nonlinear inversion has been carried out for S-wave velocities and thicknesses of the vertical profile crossing the Indian Plate,the Qinghai-Tibetan Plateau,and the Tarim Basin. It indicated that the crustal thickness is about 70 km in the Qiangtang block,while in the hinterland of the Qinghai-Tibetan Plateau the lithosphere is relatively thin(~ 130 km)from the velocity values and their offsets.

基于Matlab/Simulink的高速压力机曲柄滑块机构的动力学研究

采用联立约束法对高速压力机中曲柄滑块机构进行了动力学建模,并用Matlab/Simulink对其进行了动力学仿真分析。快速地求解出了冲压力为800KN时,不同转速下,曲轴的输入转矩、曲轴支撑处和曲轴连杆处的约束反力随时间的变化规律。仿真结果表明:随着曲轴转速的增加,曲轴的惯性力增大,引起的附加转矩增大,而且增量远大于冲压力引起的附加转矩增量。曲轴转速增加引起的约束反力增量远大于冲压力引起的约束反力增量。所得结论为高速压力机主传动形式的选择、曲柄滑块机构的动平衡结构的设计及曲轴的设计提供了研究依据。

加油站汽油营销区域协同方法及实证研究

以内蒙古地区的加油站日度价量数据为基础,利用线性回归、联立方程模型及数值模拟,研究汽油行业中存在竞争关系的加油站之间的油品价量关系,并以区域销售量为目标,对站点定价进行优化。研究发现,站点与存在竞争关系的对手站点间的油品价量互动较为频繁,各站点的促销行为将显著提高自身的汽油销量。经过模型优化后的油品销售价格能够使区域总销售额提升9%~17%,对提升区域站点竞争力具有重要意义。

高压空气复杂管网系统水舱吹除仿真研究

针对高压空气吹除水舱时剧烈气液混合流动,难以准确计算出其内部复杂流态下舱壁压力与完成吹除的所需时间,本文提出基于MPCCI平台进行一维管网和三维水舱耦合联合的仿真方法。首先建立高压空气吹除水舱数学模型,并运用Flowmaster软件对水舱吹除提供并分配动力的整个管网系统进行建模与仿真,得到各工况下管网内各节点处的压力、质量流量等参数;然后运用MpCCI平台实现Flowmaster和Fluent的联合仿真,对高压空气吹除系统进行一维管网和三维水舱耦合仿真分析,实现了吹除系统的多舱、动态和耦合的求解,得到多舱同时吹除过程中水舱中气-液混合现象、壁面压力变化及水舱排水速率等。最后对一维仿真结果与一维-三维耦合联立仿真结果进行对比,得到的水舱出口排水速率曲线有着较好的一致性。

基于替代模型和流向算法的地下水污染源反演识别

应用模拟-优化的理论和方法,对地下水污染源的相关信息、模拟模型的渗透系数以及抽水井的抽水量进行同步识别.首先,根据假想例子构建地下水污染数值模拟模型.然后,分别运用BP神经网络(BPNN)方法和核极限学习机(KELM)方法构建模拟模型的替代模型,优选出拟合精度更高的替代模型嵌入到后续的优化模型中,以此减少计算负荷并提升替代模型对模拟模型的逼近精度.最后,采用流向算法(FDA)对优化模型进行求解,得到反演结果,同时,将其分别与麻雀搜索算法(SSA)和粒子群优化算法(PSO)得到的反演结果进行对比.结果表明:相比于KELM替代模型,BPNN替代模型的拟合精度较高,确定性系数、平均相对误差和均方根误差分别为0.9999、0.1723%和0.5625;与PSO和SSA相比,FDA的收敛速度更快,对优化模型的求解精度更高,其识别结果的平均相对误差小于7%,提升了地下水污染源反演识别的精度和效率,能够为地下水污染修复、风险评定和责任认定提供可靠的依据.

收送货同时的城市无人物流配送问题研究

随着节能减碳的需求和人工智能的快速发展,以无人电动车等为配送装置的城市无人物流配送渐成现实。本文考虑电池容量约束和取送货同时装载容量约束,以最小配送成本为目标函数构建数学规划模型(E-VRPSDP);以列生成法和双向动态标签算法为基础,设计了分支定价算法实现模型的精确求解;针对大规模E-VRPSDP,设计改进模拟退火算法,引入构造可行解算子,将原始解进化成符合约束的可行解,提高了算法的搜索能力;最后,利用已有标准测试集生成测试算例以验证所设计的算法。本文可以为城市无人物流配送的发展提供理论指导和算法支持。

Simultaneous analysis of three-dimensional percolation models

We simulate the bond and site percolation models on several three-dimensional lattices, including the diamond, body-centered cubic, and face-centered cubic lattices. As on the simple-cubic lattice [Phys. Rev. E, 2013, 87（5）： 052107], it is observed that in comparison with dimensionless ratios based on cluster-size distribution, certain wrapping probabilities exhibit weaker finite-size corrections and are more sensitive to the deviation from percolation threshold Pc, and thus provide a powerful means for determining Pc. We analyze the numerical data of the wrapping probabilities simultaneously such that universal parameters are shared by the aforementioned models, and thus significantly improved estimates of Pc are obtained.

基于斜投影滤波的高精度同时极化测量方法

高精度的雷达目标同时极化测量方法对于发射波形的正交性要求较高,然而实际应用中,发射同时满足时宽、带宽以及高正交性要求的精密极化测量波形往往非常困难。提出了一种基于斜投影滤波的高精度同时极化测量方法,利用斜投影算法中两线性子空间可以不相互正交的特点,能够在非理想正交波形的实际情形下,实现高精度的目标极化测量。仿真结果表明,相较于传统的匹配滤波同时极化测量方法,该方法可以大幅降低目标极化参量的幅度和相位测量误差,极大提高同时极化测量精度。

露井同期开采诱发边坡破坏机理的研究

露井同期开采对边坡稳定性影响的问题是目前研讨的热点内容之一。以紫金山金铜矿开采活动为工程实际背景,对崩落法开采方案下露井同期开采作用下边坡破坏机理进行了模拟研究。结果表明:地下与露天合成叠加开采效应对边坡岩体稳定性影响非常大,其最大下沉值达到-7.68 m,因此必须采用高接顶率充填开采方案。露井同期开采影响下边坡岩体应力场受到两种采动同期作用,导致边坡岩体破坏更加剧烈,除要合理确定开采方案外还需考虑开采推进顺序的影响,从坡外侧向坡内推进更有利于边坡稳定性。此外由于地下和露天同期开采的复合叠加作用,地表的下沉出现多个小区域范围的下沉盆地,边坡岩体也可能产生多区域的滑动破坏体。

多本构模型参数同步更新的在线数值模拟方法研究

在线数值模拟方法是一种基于模型更新的混合试验方法,其是不完整边界条件混合试验的通用解决方案。在该方法中:结构反应由结构整体数值模型计算得到,边界条件自然得以满足;物理子结构的恢复力不再参与运动方程的求解,而是用于估计数值模型的本构参数,提高了数值模型的可靠性。论文提出多本构模型参数同步更新的在线数值模拟方法,以提高多种本构模型参数不确定性同时存在时在线数值模拟方法的精度,并以Levenberg-Marquardt算法为参数估计方法,实现了采用恢复力对钢筋和混凝土材料本构模型参数的同步估计。研究表明:以恢复力来估计材料本构模型参数是可行的,且Levenberg-Marquardt算法具有较高的收敛速度和计算精度;在线数值模拟方法有效地提高了混合试验的模拟精度。

高层建筑基础加固与上部结构同步施工分析及应用

本文通过分析软土地区某高层建筑桩基偏位和低应变检测结果,探讨了桩基事故原因。补桩方案考虑了原有工程桩的承载力和刚度贡献,通过对建筑不同类别的工程桩承载力进行分类取值,确保了方案的合理性。针对本工程建筑的特点和施工难点,采用锚杆静压桩补桩方案,解决了常规设备补桩施工空间受限、补桩和上部结构无法同步施工的难题,并减小了补桩对原有工程桩的扰动。锚杆静压桩施工过程中,为了减小补桩过程中建筑的不均匀沉降,根据建筑变形监测结果,动态调整补桩顺序。本文采用有限元方法对补桩和结构同步施工进行数值模拟,分析了补桩和结构同步施工过程中建筑的沉降变形情况。通过对比分析沉降监测数据和有限元计算结果,验证了加固方法的有效性,可应用于同类工程。